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  • 1. Ahlkrona, Josefin
    et al.
    Lötstedt, Per
    Kirchner, Nina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Zwinger, Thomas
    Dynamically coupling the non-linear Stokes equations with the shallow ice approximation in glaciology: Description and first applications of the ISCAL method2016In: Journal of Computational Physics, ISSN 0021-9991, E-ISSN 1090-2716, Vol. 308, p. 1-19Article in journal (Refereed)
    Abstract [en]

    We propose and implement a new method, called the Ice Sheet Coupled Approximation Levels (ISCAL) method, for simulation of ice sheet flow in large domains during long time-intervals. The method couples the full Stokes (FS) equations with the Shallow Ice Approximation (SIA). The part of the domain where SIA is applied is determined automatically and dynamically based on estimates of the modeling error. For a three dimensional model problem, ISCAL computes the solution substantially faster with a low reduction in accuracy compared to a monolithic FS. Furthermore, ISCAL is shown to be able to detect rapid dynamic changes in the flow. Three different error estimations are applied and compared. Finally, ISCAL is applied to the Greenland Ice Sheet on a quasi-uniform grid, proving ISCAL to be a potential valuable tool for the ice sheet modeling community.

  • 2. Ahrens, Benedikt
    et al.
    Lumsdaine, Peter Lefanu
    Stockholm University, Faculty of Science, Department of Mathematics.
    Displayed Categories2019In: Logical Methods in Computer Science, ISSN 1860-5974, E-ISSN 1860-5974, Vol. 15, no 1, article id 20Article in journal (Refereed)
    Abstract [en]

    We introduce and develop the notion of displayed categories. A displayed category over a category C is equivalent to 'a category D and functor F : D -> C', but instead of having a single collection of 'objects of D' with a map to the objects of C, the objects are given as a family indexed by objects of C, and similarly for the morphisms. This encapsulates a common way of building categories in practice, by starting with an existing category and adding extra data/properties to the objects and morphisms. The interest of this seemingly trivial reformulation is that various properties of functors are more naturally defined as properties of the corresponding displayed categories. Grothendieck fibrations, for example, when defined as certain functors, use equality on objects in their definition. When defined instead as certain displayed categories, no reference to equality on objects is required. Moreover, almost all examples of fibrations in nature are, in fact, categories whose standard construction can be seen as going via displayed categories. We therefore propose displayed categories as a basis for the development of fibrations in the type-theoretic setting, and similarly for various other notions whose classical definitions involve equality on objects. Besides giving a conceptual clarification of such issues, displayed categories also provide a powerful tool in computer formalisation, unifying and abstracting common constructions and proof techniques of category theory, and enabling modular reasoning about categories of multi-component structures. As such, most of the material of this article has been formalised in Coq over the UniMath library, with the aim of providing a practical library for use in further developments.

  • 3. Alpcan, Tansu
    et al.
    Everitt, Tom
    Stockholm University, Faculty of Science, Department of Mathematics.
    Hutter, Marcus
    Can we measure the difficulty of an optimization problem?2014Conference paper (Other academic)
    Abstract [en]

    Can we measure the difficulty of an optimization problem? Although optimization plays a crucial role in modernscience and technology, a formal framework that puts problemsand solution algorithms into a broader context has not beenestablished. This paper presents a conceptual approach which gives a positive answer to the question for a broad class of optimization problems. Adopting an information and computational perspective, the proposed framework builds upon Shannon and algorithmic information theories. As a starting point, a concrete model and definition of optimization problems is provided. Then, a formal definition of optimization difficulty is introduced which builds upon algorithmic information theory. Following an initial analysis, lower and upper bounds on optimization difficulty are established. One of the upper-bounds is closely related to Shannon information theory and black-box optimization. Finally, various computational issues and future research directions are discussed.

  • 4.
    Angelov, Krasimir
    et al.
    University of Gothenburg, Sweden.
    Liefke, KristinaGoethe University, Germany.Loukanova, RoussankaStockholm University, Faculty of Science, Department of Mathematics. Stockholm University, Faculty of Humanities, Department of Philosophy.Moortgat, MichaelUtrecht University, The Netherlands.Tojo, SatoshiSchool of Information Science, JAIST, Japan.
    Proceedings of the Symposium on Logic and Algorithms in Computational Linguistics 2018 (LACompLing2018)2018Conference proceedings (editor) (Refereed)
    Abstract [en]

    Computational linguistics studies natural language in its various manifestations from a computational point of view, both on the theoretical level (modeling grammar modules dealing with natural language form and meaning, and the relation between these two) and on the practical level (developing applications for language and speech technology). Right from the start in the 1950ties, there have been strong links with computer science, logic, and many areas of mathematics - one can think of Chomsky's contributions to the theory of formal languages and automata, or Lambek's logical modeling of natural language syntax. The symposium on Logic and Algorithms in Computational Linguistics 2018 (LACompLing2018) assesses the place of logic, mathematics, and computer science in present day computational linguistics. It intends to be a forum for presenting new results as well as work in progress.

  • 5. Angleby, Helen
    et al.
    Oskarsson, Mattias
    Pang, Junfeng
    Zhang, Ya-ping
    Leitner, Thomas
    Braham, Caitlyn
    Arvestad, Lars
    Stockholm University, Faculty of Science, Numerical Analysis and Computer Science (NADA). Stockholm University, Science for Life Laboratory (SciLifeLab).
    Lundeberg, Joakim
    Webb, Kristen M.
    Savolainen, Peter
    Forensic Informativity of similar to 3000bp of Coding Sequence of Domestic Dog mtDNA2014In: Journal of Forensic Sciences, ISSN 0022-1198, E-ISSN 1556-4029, Vol. 59, no 4, p. 898-908Article in journal (Refereed)
    Abstract [en]

    The discriminatory power of the noncoding control region (CR) of domestic dog mitochondrial DNA alone is relatively low. The extent to which the discriminatory power could be increased by analyzing additional highly variable coding regions of the mitochondrial genome (mtGenome) was therefore investigated. Genetic variability across the mtGenome was evaluated by phylogenetic analysis, and the three most variable similar to 1kb coding regions identified. We then sampled 100 Swedish dogs to represent breeds in accordance with their frequency in the Swedish population. A previously published dataset of 59 dog mtGenomes collected in the United States was also analyzed. Inclusion of the three coding regions increased the exclusion capacity considerably for the Swedish sample, from 0.920 for the CR alone to 0.964 for all four regions. The number of mtDNA types among all 159 dogs increased from 41 to 72, the four most frequent CR haplotypes being resolved into 22 different haplotypes.

  • 6.
    Aranda, Laura
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Popov, Oliver
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    A Conceptual Model of an Intelligent Platform for Security Risk Assessment in SMEs2019In: 2019 IEEE 13th International Conference on Application of Information and Communication Technologies (AICT): Conference Proceedings, IEEE, 2019Conference paper (Refereed)
    Abstract [en]

    SMEs are increasingly targeted by cyberattacks and usually less in control of their Information Security Management System than larger organizations due to a lack of resources. Risk assessment can help them to determine which changes are needed bearing in mind their constraints. However, common frameworks for risk assessments are more suitable for large organizations. Some of them have been designed specifically for SMEs but still target an audience of information security experts and are considered as time-consuming by SMEs. This article aims at tackling those issues by introducing a conceptual model of an Intelligent Platform for supporting SMEs in security risk assessment process. The design research method was used to develop a model taking into account the inputs from relevant stakeholders collected via interviews. The model was validated and improved with case studies where quick security risk assessments in three different SMEs have been performed following the activities that the proposed model is supposed to perform.

  • 7.
    Araújo, Marco
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Ekenberg, Love
    International Institute for Applied Systems Analysis (IIASA), Austria.
    Confraria, João
    School of Business & Economics, Catholic University, Portugal.
    Satellite backhaul for macro-cells, as an alternative to optical fibre, to close the digital divide2019In: 2019 IEEE Wireless Communications and Networking Conference (WCNC), IEEE, 2019Conference paper (Refereed)
    Abstract [en]

    The lack of broadband access causes a serious risk of social exclusion, by preventing citizens from full social and economic participation in the society. To avoid this risk, the concept of subsidized rural networks was developed by the European Commission, in which an operator builds, maintains and operates a network (usually an open network) capable of providing at least a 100 Mbps connection to the subscribers; deployed in low density regions being publicly subsidized when unprofitable. In this article, we suggest a methodology to measure a realistic value for the average broadband used per subscriber at busy hour. We also present a simulation model for the backhaul infrastructure costs for very fast networks in rural areas to cover the last, and more expensive, 5% of the population, while comparing optical fibre with satellite for the middle mile from an economical and financial perspective.

  • 8. Austrin, Per
    et al.
    Manokaran, Rajsekar
    Wenner, Cenny
    Stockholm University, Faculty of Science, Numerical Analysis and Computer Science (NADA). KTH - Royal Institute of Technology, Sweden.
    On the NP-Hardness of Approximating Ordering-Constraint Satisfaction Problems2015In: Theory of Computing, ISSN 1557-2862, E-ISSN 1557-2862, Vol. 11, article id 10Article in journal (Refereed)
    Abstract [en]

    We show improved NP-hardness of approximating Ordering Constraint Satis-faction Problems (OCSPs). For the two most well-studied OCSPs, Maximum Acyclic Subgraph and Maximum Betweenness, we prove NP-hard approximation factors of 14/15+ε and 1/2+ε. When it is hard to approximate an OCSP by a constant better than takinga uniformly-at-random ordering, then the OCSP is said to be approximation resistant. We show that the Maximum Non-Betweenness Problem is approximation resistant and that there are width-m approximation-resistant OCSPs accepting only a fraction 1/(m/2)! of assignments. These results provide the first examples of approximation-resistant OCSPs only to P != NP.

  • 9.
    Ayele, Workneh Yilma
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Juell-Skielse, Gustaf
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Social Media Analytics and Internet of Things: Survey2017In: Proceedings of the 1st International Conference on Internet of Things and Machine Learning, Association for Computing Machinery (ACM), 2017, article id 53Conference paper (Refereed)
    Abstract [en]

    Due to the emergence of social media, there is a paradigm shift in the area of information production, processing and consumption. Hence, investigation in the utilization of open social media data is a relevant research topic. The openness of data, social media data, enables innovation and societal value creation. Social media analytics is an evolving research domain with interdisciplinary methods that are common in data mining such as text mining, social network analysis, trend analysis, and sentiment analysis. Also, social media analytics deals with development and evaluation of frameworks and informatics tools to process noisy and unstructured social media data. On the other hand, Internet of Things (IoT) enables the utilization of digital artifacts with well-established solutions and allows things to be connected regardless of location and time. However, a literature review about social media analytics and IoT integration is missing. In this paper, we conducted a systematic literature review of social media analytics and IoT integration. The literature review indicates that there are fewer research works done in the area of social media analytics and IoT compared to Data Mining and IoT. This paper facilitates discussion and elicits research potentials in social media analytics and IoT integration.

  • 10.
    Azari, Amin
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Papapetrou, Panagiotis
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Denic, Stojan
    Peters, Gunnar
    Cellular Traffic Prediction and Classification: A Comparative Evaluation of LSTM and ARIMA2019In: Discovery Science: Proceedings / [ed] Petra Kralj Novak, Tomislav, Šmuc, Sašo Džeroski, Springer, 2019, p. 129-144Conference paper (Refereed)
    Abstract [en]

    Prediction of user traffic in cellular networks has attracted profound attention for improving the reliability and efficiency of network resource utilization. In this paper, we study the problem of cellular network traffic prediction and classification by employing standard machine learning and statistical learning time series prediction methods, including long short-term memory (LSTM) and autoregressive integrated moving average (ARIMA), respectively. We present an extensive experimental evaluation of the designed tools over a real network traffic dataset. Within this analysis, we explore the impact of different parameters on the effectiveness of the predictions. We further extend our analysis to the problem of network traffic classification and prediction of traffic bursts. The results, on the one hand, demonstrate the superior performance of LSTM over ARIMA in general, especially when the length of the training dataset is large enough and its granularity is fine enough. On the other hand, the results shed light onto the circumstances in which, ARIMA performs close to the optimal with lower complexity.

  • 11.
    Bampa, Maria
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Papapetrou, Panagiotis
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Aggregate-Eliminate-Predict: Detecting Adverse Drug Events from Heterogeneous Electronic Health Records2019Manuscript (preprint) (Other academic)
    Abstract [en]

    We study the problem of detecting adverse drug events in electronic healthcare records. The challenge in this work is to aggregate heterogeneous data types involving diagnosis codes, drug codes, as well as lab measurements. An earlier framework proposed for the same problem demonstrated promising predictive performance for the random forest classifier by using only lab measurements as data features. We extend this framework, by additionally including diagnosis and drug prescription codes, concurrently. In addition, we employ a recursive feature selection mechanism on top, that extracts the top-k most important features. Our experimental evaluation on five medical datasets of adverse drug events and six different classifiers, suggests that the integration of these additional features provides substantial and statistically significant improvements in terms of AUC, while employing medically relevant features.

  • 12.
    Bampa, Maria
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Papapetrou, Panagiotis
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Mining Adverse Drug Events Using Multiple Feature Hierarchies and Patient History Windows2019In: 19th IEEE International Conference on Data Mining Workshops: Proceedings / [ed] Panagiotis Papapetrou, Xueqi Cheng, Qing He, IEEE, 2019Conference paper (Refereed)
    Abstract [en]

    We study the problem of detecting adverse drug events in electronic health records. The challenge is this work is to aggregate heterogeneous data types involving lab measurements, diagnoses codes and medications codes. An earlier framework proposed for the same problem demonstrated promising predictive performance for the random forest classifier by using only lab measurements as data features. We extend this framework, by additionally including diagnosis and drug prescription codes, concurrently. In addition, we employ the concept of hierarchies of clinical codes as proposed by another work, in order to exploit the inherently complex nature of the medical data. Moreover, we extended the state-of-the-art by considering variable patient history lengths before the occurrence of an ADE event rather than a patient history of an arbitrary length. Our experimental evaluation on eight medical datasets of adverse drug events, five different patient history lengths, and six different classifiers, suggests that the integration of these additional features on the different window lengths provides significant improvements in terms of AUC while employing medically relevant features.

  • 13.
    Berthet, Pierre
    et al.
    Stockholm University, Faculty of Science, Numerical Analysis and Computer Science (NADA). Royal Institute of Technology, Sweden.
    Hellgren-Kotaleski, Jeanette
    Lansner, Anders
    Stockholm University, Faculty of Science, Numerical Analysis and Computer Science (NADA). Royal Institute of Technology, Sweden.
    Action selection performance of a reconfigurable basal ganglia inspired model with Hebbian-Bayesian Go- NoGo connectivity2012In: Frontiers in Behavioral Neuroscience, ISSN 1662-5153, E-ISSN 1662-5153, Vol. 6, article id 65Article in journal (Refereed)
    Abstract [en]

    Several studies have shown a strong involvement of the basal ganglia (BG) in action selection and dopamine dependent learning. The dopaminergic signal to striatum, the input stage of the BG, has been commonly described as coding a reward prediction error (RPE), i.e., the difference between the predicted and actual reward. The RPE has been hypothesized to be critical in the modulation of the synaptic plasticity in cortico-striatal synapses in the direct and indirect pathway. We developed an abstract computational model of the BG, with a dual pathway structure functionally corresponding to the direct and indirect pathways, and compared its behavior to biological data as well as other reinforcement learning models. The computations in our model are inspired by Bayesian inference, and the synaptic plasticity changes depend on a three factor Hebbian-Bayesian learning rule based on co-activation of pre- and post-synaptic units and on the value of the RPE. The model builds on a modified Actor-Critic architecture and implements the direct (Go) and the indirect(NoGo) pathway, as well as the reward prediction (RP) system, acting in a complementary fashion. We investigated the performance of the model system when different configurations of the Go, NoGo, and RP system were utilized, e.g., using only the Go, NoGo, or RP system, or combinations of those. Learning performance was investigated in several types of learning paradigms, such as learning-relearning, successive learning, stochastic learning, reversal learning and a two-choice task. The RPE and the activity of the model during learning were similar to monkey electrophysiological and behavioral data. Our results, however, show that there is not a unique best way to configure this BG model to handle well all the learning paradigms tested. We thus suggest that an agent might dynamically configure its action selection mode, possibly depending on task characteristics and also on how much time is available.

  • 14.
    Berthet, Pierre
    et al.
    Stockholm University, Faculty of Science, Numerical Analysis and Computer Science (NADA). Royal Institute of Technology, Sweden.
    Lansner, Anders
    Stockholm University, Faculty of Science, Numerical Analysis and Computer Science (NADA). Royal Institute of Technology, Sweden.
    Optogenetic Stimulation in a Computational Model of the Basal Ganglia Biases Action Selection and Reward Prediction Error2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 3, article id e90578Article in journal (Refereed)
    Abstract [en]

    Optogenetic stimulation of specific types of medium spiny neurons (MSNs) in the striatum has been shown to bias the selection of mice in a two choices task. This shift is dependent on the localisation and on the intensity of the stimulation but also on the recent reward history. We have implemented a way to simulate this increased activity produced by the optical flash in our computational model of the basal ganglia (BG). This abstract model features the direct and indirect pathways commonly described in biology, and a reward prediction pathway (RP). The framework is similar to Actor-Critic methods and to the ventral/ dorsal distinction in the striatum. We thus investigated the impact on the selection caused by an added stimulation in each of the three pathways. We were able to reproduce in our model the bias in action selection observed in mice. Our results also showed that biasing the reward prediction is sufficient to create a modification in the action selection. However, we had to increase the percentage of trials with stimulation relative to that in experiments in order to impact the selection. We found that increasing only the reward prediction had a different effect if the stimulation in RP was action dependent (only for a specific action) or not. We further looked at the evolution of the change in the weights depending on the stage of learning within a block. A bias in RP impacts the plasticity differently depending on that stage but also on the outcome. It remains to experimentally test how the dopaminergic neurons are affected by specific stimulations of neurons in the striatum and to relate data to predictions of our model.

  • 15.
    Beskow, Jonas
    et al.
    KTH Speech, Music and Hearing.
    Carlson, Rolf
    KTH Speech, Music and Hearing.
    Edlund, Jens
    KTH Speech, Music and Hearing.
    Granström, Björn
    KTH Speech, Music and Hearing.
    Heldner, Mattias
    KTH Speech, Music and Hearing.
    Hjalmarsson, Anna
    KTH Speech, Music and Hearing.
    Skantze, Gabriel
    KTH Speech, Music and Hearing.
    Multimodal Interaction Control2009In: Computers in the Human Interaction Loop / [ed] Waibel, Alex and Stiefelhagen, Rainer, Berlin/Heidelberg: Springer Berlin/Heidelberg, 2009, p. 143-158Chapter in book (Refereed)
  • 16.
    Beskow, Jonas
    et al.
    KTH Speech, Music and Hearing.
    Edlund, Jens
    KTH Speech, Music and Hearing.
    Gustafson, Joakim
    KTH Speech, Music and Hearing.
    Heldner, Mattias
    KTH Speech, Music and Hearing.
    Hjalmarsson, Anna
    KTH Speech, Music and Hearing.
    House, David
    KTH Speech, Music and Hearing.
    Research focus: Interactional aspects of spoken face-to-face communication2010In: Proceedings from Fonetik 2010, Lund: Lund University , 2010, p. 7-10Conference paper (Other academic)
  • 17. Boström, Henrik
    et al.
    Asker, Lars
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Gurung, Ram B.
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Karlsson, Isak
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Lindgren, Tony
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Papapetrou, Panagiotis
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Conformal prediction using random survival forests2017In: 16th IEEE International Conference on Machine Learning and Applications: Proceedings / [ed] Xuewen Chen, Bo Luo, Feng Luo, Vasile Palade, M. Arif Wani, IEEE, 2017, p. 812-817Conference paper (Refereed)
    Abstract [en]

    Random survival forests constitute a robust approach to survival modeling, i.e., predicting the probability that an event will occur before or on a given point in time. Similar to most standard predictive models, no guarantee for the prediction error is provided for this model, which instead typically is empirically evaluated. Conformal prediction is a rather recent framework, which allows the error of a model to be determined by a user specified confidence level, something which is achieved by considering set rather than point predictions. The framework, which has been applied to some of the most popular classification and regression techniques, is here for the first time applied to survival modeling, through random survival forests. An empirical investigation is presented where the technique is evaluated on datasets from two real-world applications; predicting component failure in trucks using operational data and predicting survival and treatment of heart failure patients from administrative healthcare data. The experimental results show that the error levels indeed are very close to the provided confidence levels, as guaranteed by the conformal prediction framework, and that the error for predicting each outcome, i.e., event or no-event, can be controlled separately. The latter may, however, lead to less informative predictions, i.e., larger prediction sets, in case the class distribution is heavily imbalanced.

  • 18.
    Boye, Johan
    et al.
    TeliaSonera.
    Wirén, Mats
    TeliaSonera.
    Multi-slot semantics for natural-language call routing systems2007In: Proceedings of Bridging the Gap: Academic and Industrial Research in Dialog Technology, 2007, p. 68-75Conference paper (Refereed)
    Abstract [en]

    Statistical classification techniques for natural-language call routing systems have matured to the point where it is possible to distinguish between several hundreds of semantic categories with an accuracy that is sufficient for commercial deployments. For category sets of this size, the problem of maintaining consistency among manually tagged utterances becomes limiting, as lack of consistency in the training data will degrade performance of the classifier. It is thus essential that the set of categories be structured in a way that alleviates this problem, and enables consistency to be preserved as the domain keeps changing. In this paper, we describe our experiences of using a two-level multi-slot semantics as a way of meeting this problem. Furthermore, we explore the ramifications of the approach with respect to classification, evaluation and dialogue design for call routing systems.

  • 19.
    Brouwers, Lisa
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Microsimulation Models for Disaster Policy Making2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Two executable simulation models for answering policy questions were designed and implemented. The first for a flood management case, and the second for a disease transmission case that is currently underway. The flood simulation model differs from earlier natural disaster simulation models in several respects. It represents explicitly the geographical location and the economic strength of each household. It is also equipped with a graphical user interface, making it possible to design policies interactively, and to test their outcomes. If policy options are compared, the simulation results can automatically be transformed into decision trees. The flood simulation model shows that a micro-level representation makes it possible to investigate the distributional effects of policy changes. Novel features of the disease transmission model include the use of (anonymized) data representing nine million individuals, the inclusion of important parts of the contact patterns, and the explicit representation of places. The disease transmission model shows that the incorporation of social structure allows for a more realistic representation of disease spread than do models that assume homogenous mixing. Using this model, it is possible to conduct experiments of significant policy relevance, such as investigating the initial growth of an epidemic on a real-world network. Together, the two cases demonstrate the usefulness of a spatially explicit micro-level representation for policy simulation models in the area of disaster management.

  • 20.
    Brouwers, Lisa
    et al.
    KTH.
    Cakici, Baki
    KTH.
    Camitz, Martin
    Swedish Institute for Infectious Control (SMI).
    Tegnell, Anders
    National Board of Health and Welfare.
    Boman, Magnus
    KTH.
    Economic consequences to society of pandemic H1N1 influenza 2009 – preliminary results for Sweden2009In: Eurosurveillance, ISSN 1025-496X, E-ISSN 1560-7917, Vol. 14, no 37Article in journal (Refereed)
  • 21.
    Cakici, Baki
    et al.
    KTH.
    Boman, Magnus
    KTH.
    A Workflow for Software Development within Computational Epidemiology2011In: Journal of Computational Science, ISSN 1877-7503, Vol. 2, no 3, p. 216-222Article in journal (Refereed)
    Abstract [en]

    A critical investigation into computational models developed for studying the spread of communicable disease is presented. The case in point is a spatially explicit micro-meso-macro model for the entire Swedish population built on registry data, thus far used for smallpox and for influenza-like illnesses. The lessons learned from a software development project of more than 100 person months are collected into a check list. The list is intended for use by computational epidemiologists and policy makers, and the workflow incorporating these two roles is described in detail.

  • 22.
    Ceci, Michelangelo
    et al.
    Università degli Studi di Bari Aldo Moro, Bari, Italy.
    Hollmén, JaakkoStockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.Todorovski, LjupčoUniversity of Ljubljana, Ljubljana, Slovenia.Vens, CelineKU Leuven Kulak, Kortrijk, Belgium.Džeroski, SašoJožef Stefan Institute, Ljubljana, Slovenia.
    Machine Learning and Knowledge Discovery in Databases: European Conference, ECML PKDD 2017, Skopje, Macedonia, September 18–22, 2017, Proceedings, Part I2017Conference proceedings (editor) (Other academic)
    Abstract [en]

    The three volume proceedings LNAI 10534 – 10536 constitutes the refereed proceedings of the European Conference on Machine Learning and Knowledge Discovery in Databases, ECML PKDD 2017, held in Skopje, Macedonia, in September 2017. The total of 101 regular papers presented in part I and part II was carefully reviewed and selected from 364 submissions; there are 47 papers in the applied data science, nectar and demo track. The contributions were organized in topical sections named as follows: Part I: anomaly detection; computer vision; ensembles and meta learning; feature selection and extraction; kernel methods; learning and optimization, matrix and tensor factorization; networks and graphs; neural networks and deep learning. Part II: pattern and sequence mining; privacy and security; probabilistic models and methods; recommendation; regression; reinforcement learning; subgroup discovery; time series and streams; transfer and multi-task learning; unsupervised and semisupervised learning. Part III: applied data science track; nectar track; and demo track.

  • 23.
    Ceci, Michelangelo
    et al.
    Università degli Studi di Bari Aldo Moro, Bari, Italy.
    Hollmén, JaakkoStockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.Todorovski, LjupčoUniversity of Ljubljana, Ljubljana, Slovenia.Vens, CelineKU Leuven Kulak, Kortrijk, Belgium.Džeroski, SašoJožef Stefan Institute, Ljubljana, Slovenia.
    Machine Learning and Knowledge Discovery in Databases: European Conference, ECML PKDD 2017, Skopje, Macedonia, September 18–22, 2017, Proceedings, Part II2017Conference proceedings (editor) (Other academic)
    Abstract [en]

    The three volume proceedings LNAI 10534 – 10536 constitutes the refereed proceedings of the European Conference on Machine Learning and Knowledge Discovery in Databases, ECML PKDD 2017, held in Skopje, Macedonia, in September 2017. The total of 101 regular papers presented in part I and part II was carefully reviewed and selected from 364 submissions; there are 47 papers in the applied data science, nectar and demo track. The contributions were organized in topical sections named as follows: Part I: anomaly detection; computer vision; ensembles and meta learning; feature selection and extraction; kernel methods; learning and optimization, matrix and tensor factorization; networks and graphs; neural networks and deep learning. Part II: pattern and sequence mining; privacy and security; probabilistic models and methods; recommendation; regression; reinforcement learning; subgroup discovery; time series and streams; transfer and multi-task learning; unsupervised and semisupervised learning. Part III: applied data science track; nectar track; and demo track.

  • 24. Cerrito, Serenella
    et al.
    David, Amélie
    Goranko, Valentin
    Stockholm University, Faculty of Humanities, Department of Philosophy.
    Optimal Tableaux Method for Constructive Satisfiability Testing and Model Synthesis in the Alternating-time Temoral Logic ATL+2015In: ACM Transactions on Computational Logic, ISSN 1529-3785, E-ISSN 1557-945X, Vol. 17, no 1, article id 4Article in journal (Refereed)
    Abstract [en]

    We develop a sound, complete, and practically implementable tableau-based decision method for constructive satisfiability testing and model synthesis for the fragment ATL+ of the full alternating-time temporal logic ALT*. The method extends in an essential way a previously developed tableau-based decision method for ATL and works in 2EXPTIME, which is the optimal worst-case complexity of the satisfiability problem for ATL+. We also discuss how suitable parameterizations and syntactic restrictions on the class of input ATL+formulas can reduce the complexity of the satisfiability problem.

  • 25. Crielaard, Loes
    et al.
    Papapetrou, Panagiotis
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Explainable predictions of adverse drug events from electronic health records via oracle coaching2018In: 2018 IEEE International Conference on Data Mining Workshops (ICDMW): Proceedings, IEEE, 2018, p. 707-714Conference paper (Refereed)
    Abstract [en]

    Information about drug efficacy and safety is limited despite current research on adverse drug events (ADEs). Electronic health records (EHRs) may be an overcoming medium, however the application and evaluation of predictive models for ADE detection based on EHRs focus primarily on predictive performance with little emphasis on explainability and clinical relevance of the obtained predictions. This paper therefore aims to provide new means for obtaining explainable and clinically relevant predictions and medical pathways underlying ADEs, by deriving sets of rules leading to explainable ADE predictions via oracle coaching and indirect rule induction. This is achieved by mapping opaque random forest models to explainable decision trees without compromising predictive performance. The results suggest that the average performance of decision trees with oracle coaching exceeds that of random forests for all considered metrics for the task of ADE detection. Relationships between many patient features present in the rulesets and the ADEs appear to exist, however not conforming to the causal pathways implied by the models - which emphasises the need for explainable predictions.

  • 26.
    Cöster, Rickard
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Algorithms and Representations for Personalised Information Access2005Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Personalised information access systems use historical feedback data, such as implicit and explicit ratings for textual documents and other items, to better locate the right or relevant information for individual users.

    Three topics in personalised information access are addressed: learning from relevance feedback and document categorisation by the use of concept-based text representations, the need for scalable and accurate algorithms for collaborative filtering, and the integration of textual and collaborative information access.

    Two concept-based representations are investigated that both map a sparse high-dimensional term space to a dense concept space. For learning from relevance feedback, it is found that the representation combined with the proposed learning algorithm can improve the results of novel queries, when queries are more elaborate than a few terms. For document categorisation, the representation is found useful as a complement to a traditional word-based one.

    For collaborative filtering, two algorithms are proposed: the first for the case where there are a large number of users and items, and the second for use in a mobile device. It is demonstrated that memory-based collaborative filtering can be more efficiently implemented using inverted files, with equal or better accuracy, and that there is little reason to use the traditional in-memory vector approach when the data is sparse. An empirical evaluation of the algorithm for collaborative filtering on mobile devices show that it can generate accurate predictions at a high speed using a small amount of resources.

    For integration, a system architecture is proposed where various combinations of content-based and collaborative filtering can be implemented. The architecture is general in the sense that it provides an abstract representation of documents and user profiles, and provides a mechanism for incorporating new retrieval and filtering algorithms at any time.

    In conclusion this thesis demonstrates that information access systems can be personalised using scalable and accurate algorithms and representations for the increased benefit of the user.

  • 27.
    Danielson, Mats
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Ekenberg, Love
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Larsson, Aron
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Riabacke, Mona
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Weighting Under Ambiguous Preferences and Imprecise Differences in a Cardinal Rank Ordering Process2014In: International Journal of Computational Intelligence Systems, ISSN 1875-6891, Vol. 7, no S1, p. 105-112Article in journal (Refereed)
    Abstract [en]

    The limited amount of good tools for supporting elicitation of preference information in multi-criteria decision analysis (MCDA) causes practical problem. In our experiences, this can be remedied by allowing more relaxed input statements from decision-makers, causing the elicitation process to be less cognitively demanding. Furthermore, it should not be too time consuming and must be able to actually use of the information the decision-maker is able to supply. In this paper, we propose a useful weight elicitation method for MAVT/MAUT decision making, which builds on the ideas of rank-order methods, but increases the precision by adding numerically imprecise cardinal information as well.

  • 28.
    De Masellis, Riccardo
    et al.
    Stockholm University, Faculty of Humanities, Department of Philosophy.
    Goranko, Valentin
    Stockholm University, Faculty of Humanities, Department of Philosophy. University of Johannesburg, South Africa.
    Gruner, Stefan
    Timm, Nils
    Generalising the Dining Philosophers Problem: Competitive Dynamic Resource Allocation in Multi-agent Systems2019In: Multi-Agent Systems: Revised Selected Papers / [ed] Marija Slavkovik, Springer, 2019, p. 30-47Conference paper (Refereed)
    Abstract [en]

    We consider a new generalisation of the Dining Philosophers problem with a set of agents and a set of resource units which can be accessed by them according to a fixed graph of accessibility between agents and resources. Each agent needs to accumulate a certain (fixed for the agent) number of accessible resource units to accomplish its task, and once it is accomplished the agent releases all resources and starts accumulating them again. All this happens in succession of discrete ‘rounds’ and yields a concurrent game model of ‘dynamic resource allocation’. We use the Alternating time Temporal Logic (ATL) to specify important properties, such as goal achievability, fairness, deadlock, starvation, etc. These can be formally verified using the efficient model checking algorithm for ATL. However, the sizes of the resulting explicit concurrent game models are generally exponential both in the number of resources and the number of agents, which makes the ATL model checking procedure generally intractable on such models, especially when the number of resources is large. That is why we also develop an abstract representation of the dynamic resource allocation models and develop a symbolic version of the model checking procedure for ATL. That symbolic procedure reduces the time complexity of model checking to polynomial in the number of resources, though it can take a worst-case double exponential time in the number of agents.

  • 29. Demri, Stephane
    et al.
    Goranko, Valentin
    Stockholm University, Faculty of Humanities, Department of Philosophy.
    Lange, Martin
    Temporal logics in computer science: Finite-state systems2016Book (Other academic)
    Abstract [en]

    This comprehensive text provides a modern and technically precise exposition of the fundamental theory and applications of temporal logics in computer science. Part I presents the basics of discrete transition systems, including constructions and behavioural equivalences. Part II examines the most important temporal logics for transition systems and Part III looks at their expressiveness and complexity. Finally, Part IV describes the main computational methods and decision procedures for model checking and model building - based on tableaux, automata and games - and discusses their relationships. The book contains a wealth of examples and exercises, as well as an extensive annotated bibliography. Thus, the book is not only a solid professional reference for researchers in the field but also a comprehensive graduate textbook that can be used for self-study as well as for teaching courses.

  • 30.
    Dudas, Catarina
    et al.
    Högskolan i Skövde, Institutionen för teknik och samhälle.
    Ng, Amos
    Högskolan i Skövde, Institutionen för teknik och samhälle.
    Boström, Henrik
    Högskolan i Skövde, Institutionen för kommunikation och information.
    Knowledge Extraction in Manufacturing using Data Mining Techniques2008In: Proceedings of the Swedish Production Symposium 2008, Stockholm, Sweden, November 18-20, 2008, 2008, p. 8 sidor-Conference paper (Refereed)
    Abstract [en]

    Nowadays many production companies collect and store production and process data in large databases. Unfortunately the data is rarely used in the most value generating way, i.e.,  finding  patterns  of  inconsistencies  and  relationships  between  process  settings  and quality  outcome.  This  paper  addresses  the  benefits  of  using  data  mining  techniques  in manufacturing  applications.  Two  different  applications  are  being  laid  out  but  the  used technique  and  software  is  the  same  in  both  cases.  The  first  case  deals  with  how  data mining  can  be  used  to  discover  the  affect  of  process  timing  and  settings  on  the  quality outcome in the casting industry. The result of a multi objective optimization of a camshaft process  is  being  used  as  the  second  case.  This  study  focuses  on  finding  the  most appropriate dispatching rule settings in the buffers on the line.  The  use  of  data  mining  techniques  in  these  two  cases  generated  previously  unknown knowledge. For example, in order to maximize throughput in the camshaft production, let the dispatching rule for the most severe bottleneck be of type Shortest Processing Time (SPT) and for the second bottleneck use any but Most Work Remaining (MWKR).

  • 31.
    Edirisuriya, Ananda
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Design Support for e-Commerce Information Systems using Goal, Business and Process Modelling  2009Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Enterprises use various models to find design solutions to their e-Commerce information systems. Goal, business and process models are parts of a chain of models used for this purpose. Business modelling requires structured methods to support design and traceability. Process modelling also needs structured methods to manage design complexity, traceability and flexibility. The thesis proposes several artifacts to address these challenges.

     It proposes a method to design business models from goal models. We start by analyzing strategic goals and express goal model notions using business notions. A set of guidelines is proposed to design a business model. The method provides structured business model design and traceability of the decisions from business to strategic level.

    The thesis also discusses a set of mappings to relate goal modelling language constructs to process modelling notions. We use BMM, i* and KAOS for goal modelling. The mappings are used to identify how these techniques can support process design. In addition, a set of mappings is proposed to relate business modelling language constructs to process modelling notions. We use the e3value model for business modelling. Based on these mappings a number of activities are identified to structure process activities from a business viewpoint.

    We also propose a method to design process models using goal and business models as inputs. As a bridge between two input models and a process model, the notion of an activity dependency model is introduced. The transitions between models are performed by using guidelines. The method provides structured process model design, flexibility for process models and traceability of the decisions from operational to strategic and business levels.

    These artifacts can be used for designing enterprise business and process models. We follow the design science research method used in information systems research. The evaluation builds on scenarios, implementations and a literature review.

  • 32.
    Edlund, Jens
    et al.
    KTH Speech, Music and Hearing.
    Gustafson, Joakim
    KTH Speech, Music and Hearing.
    Heldner, Mattias
    KTH Speech, Music and Hearing.
    Hjalmarsson, Anna
    KTH Speech, Music and Hearing.
    Towards human-like spoken dialogue systems2008In: Speech Communication, ISSN 0167-6393, E-ISSN 1872-7182, Vol. 50, no 8-9, p. 630-645Article in journal (Refereed)
    Abstract [en]

    This paper presents an overview of methods that can be used to collect and analyse data on user responses to spoken dialogue system components intended to increase human-likeness, and to evaluate how well the components succeed in reaching that goal. Wizard-of-Oz variations, human-human data manipulation, and micro-domains are discussed ill this context, as is the use of third-party reviewers to get a measure of the degree of human-likeness. We also present the two-way mimicry target, a model for measuring how well a human-computer dialogue mimics or replicates some aspect of human-human dialogue, including human flaws and inconsistencies. Although we have added a measure of innovation, none of the techniques is new in its entirely. Taken together and described from a human-likeness perspective, however, they form a set of tools that may widen the path towards human-like spoken dialogue systems.

  • 33.
    Edlund, Jens
    et al.
    KTH Speech, Music and Hearing.
    Heldner, Mattias
    KTH Speech, Music and Hearing.
    Exploring prosody in interaction control2005In: Phonetica, ISSN 0031-8388, E-ISSN 1423-0321, Vol. 62, no 2-4, p. 215-226Article in journal (Refereed)
    Abstract [en]

    This paper investigates prosodic aspects of turn-taking in conversation with a view to improving the efficiency of identifying relevant places at which a machine can legitimately begin to talk to a human interlocutor. It examines the relationship between interaction control, the communicative function of which is to regulate the flow of information between interlocutors, and its phonetic manifestation. Specifically, the listener's perception of such interaction control phenomena is modelled. Algorithms for automatic online extraction of prosodic phenomena liable to be relevant for interaction control, such as silent pauses and intonation patterns, are presented and evaluated in experiments using Swedish map task data. We show that the automatically extracted prosodic features can be used to avoid many of the places where current dialogue systems run the risk of interrupting their users, as well as to identify suitable places to take the turn.

  • 34.
    Edlund, Jens
    et al.
    KTH Speech, Music and Hearing.
    Heldner, Mattias
    KTH Speech, Music and Hearing.
    Underpinning /nailon/: automatic estimation of pitch range and speaker relative pitch2007In: Speaker Classification II / [ed] Müller, Christian, Berlin/Heidelberg, Germany: Springer Berlin/Heidelberg, 2007, p. 229-242Chapter in book (Refereed)
  • 35.
    Edlund, Jens
    et al.
    KTH Speech, Music and Hearing.
    Heldner, Mattias
    KTH Speech, Music and Hearing.
    Al Moubayed, Samer
    KTH Speech, Music and Hearing.
    Gravano, Agustìn
    Hirschberg, Julia
    Columbia University Computer Science.
    Very short utterances in conversation2010In: Proceedings from Fonetik 2010, Lund: Lund University , 2010, p. 11-16Conference paper (Other academic)
  • 36.
    Edlund, Jens
    et al.
    KTH Speech, Music and Hearing.
    Heldner, Mattias
    KTH Speech, Music and Hearing.
    Hirschberg, Julia
    Columbia University Computer Science.
    Pause and gap length in face-to-face interaction2009In: Proceedings of Interspeech 2009, Brighton, UK: ISCA , 2009, p. 2779-2782Conference paper (Refereed)
  • 37.
    Edlund, Jens
    et al.
    KTH Speech, Music and Hearing.
    Heldner, Mattias
    KTH Speech, Music and Hearing.
    Pelcé, Antoine
    KTH Speech, Music and Hearing.
    Prosodic features of very short utterances in dialogue2009In: Nordic Prosody: Proceedings of the Xth Conference, Helsinki 2008, Frankfurt am Main: Peter Lang Publishing Group, 2009, p. 57-68Conference paper (Refereed)
  • 38.
    Eiderbäck, Björn
    Stockholm University.
    Object oriented frameworks with design patterns for building distributed information sharing2001Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The construction and programming of interactive graphical user interfaces is hard work with conventional programming tools. Investigations have shown that as much as 80% of the programming code could be related to the interactive parts in modern applications with a graphical interface.

    Another difficult task is the development of distributed applications. There are several frameworks and packages around for development of distributed interactive applications, but none is fully satisfactory, and more research and development is needed.

    Interest in applications that provide Computer Supported Co-operative Work (CSCW) is rapidly growing, particularly during the recent years with increasing interest in Internet solutions. CSCW applications are usually interactive and, in one way or another, distributed. It is a challenge to provide mechanisms and tools that allow rapid and easy development of interactive and distributed applications. Another challenge is the development of various means for sharing information. Different applications require different types of sharing and a particular application may require several sharing mechanisms. Two major challenges for an application are the ability to allow users to view data in different ways and the possibility of tailoring the interface to meet the different needs of different users. Therefore, further development of frameworks, tools, and modern interface-builders is required. In particular, we need better means for experimenting with and prototyping new ideas for CSCW applications.

    In this thesis, I define a framework of high-level mechanisms for the interactive distribution and sharing of information, founded on the object-oriented paradigm. The mechanisms are demonstrated as extensions to the existing class library of a Smalltalk environment. I describe how I have integrated the framework into the Interface Building tools of the environment, and in this way obtained a system that allows rapid development and easy experimentation with many techniques.

    Another aim of this thesis is to develop and demonstrate ways to describe essential structures, solutions, and intentions using powerful explanatory techniques. This means that the way the descriptions are made has a value in itself. One particular reason for exploring such techniques is that traditional techniques are either too weak, too imprecise, or too formal to be of real practical value. However, traditional techniques are very useful for defining overall structures, collaborations between components, algorithms, and more intricate functionality. But they are not usually suitable for communicating the essence and intentions of the software. I believe that it will become more important to communicate the structures of software solutions, as applications become more complex. Further, the software market is becoming ever more competitive, and a short time to market is necessary to provide competitive advantage. Design patterns a new field of research and development, has recently emerged. With design patterns one can make clear descriptions of soft-ware application and therefore contribute to shorten the time taken for applications to reach the market. In this thesis I use design patterns as the main ingredient when describing a particular software structure or solution.

  • 39.
    Ekanayake, Hiran B.
    et al.
    University of Colombo School of Computing, Sri Lanka.
    Karunarathna, Damitha D.
    University of Colombo School of Computing, Sri Lanka.
    Hewagamage, Kamalanath P.
    University of Colombo School of Computing, Sri Lanka.
    Determining the Psychological Involvement in Multimedia Interactions2009In: The International Journal on Advances in ICT for Emerging Regions, ISSN 1800-4156, Vol. 2, no 1Article in journal (Refereed)
    Abstract [en]

    Human computer interaction (HCI) is currently aimed at the design of interactive computer applications for human use while preventing user frustration. When considering the nature of modern computer applications, such as e-learning systems and computer games, it appears that human involvement cannot be improved only by using traditional approaches, such as nice user interfaces. For a pleasant human involvement, these computer applications require that the computers should have the ability to naturally adapt to their users and this requires the computers to have the ability to recognize user emotions. For recognizing emotions currently most preferred research approach is aimed at facial expression based emotion recognition, which seems to have many limitations. Therefore, in this paper, we propose a method to determine the psychological involvement of a human during a multimedia interaction session using the eye movement activity and arousal evaluation. In our approach we use a low cost hardware/software combination, which determines eye movement activity based on electrooculogram (EOG) signals and the level of arousal using galvanic skin response (GSR) signals. The results obtained using six individuals show that the nature of involvement can be recognized using these affect signals as optimal levels and distracted conditions.

  • 40.
    Ekenberg, Love
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Decision support in numerically imprecise domains1994Doctoral thesis, monograph (Other academic)
  • 41.
    Eriksson-Granskog, Agneta
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    General Metarules for Interactive Modular Construction of Natural Deduction Proofs2003Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This thesis proposes a set of general metarules for interactive modular construction of natural deduction proofs.

    Interactive proof support systems are used for the construction of formal proofs in formal program development. They support the user interaction in the derivation of programs from specifications and in the development of proofs of properties of programs. Moreover, interactive proof support systems are often general theorem provers and provide general support for proof development. Natural deduction with its similarity to intuitive informal reasoning and its lucid proof explanations is ideal for interactive proof development. However, the formal proofs in formal program development tend to be long and detailed, and metarules for the development of proofs in natural deduction would give shorter proofs and facilitate the user interaction.

    The focus of the thesis is the characterization of general metarules for the interactive construction of proofs in natural deduction. The solution presented supports modularity and flexibility in interactive proof development and it provides interactive construction of proofs at metalevel and facilitates the presentation of the proofs at different levels of abstraction.

    The main contributions are:

    · General metarules for modular proof development.

    The general metarules for the interactive construction of derivations in natural deduction support the construction of proofs from proof parts. They compute parts of proofs on the demand of the user. By computing derived rules for each application, a user has important leeway in the number of rules to use.

    · Flexibility in the development of proofs.

    The flexibility in the interactive development of proofs is supported by general metarules for changes. The method for performing changes to proofs is based upon the replacement of parts of proofs.

    · A proof structure supporting the development of fragmentary proofs.

    · Explanations of proofs at different levels in accordance with the inference rules of natural deduction and the general metarules.

  • 42.
    Esteban, Pablo G.
    et al.
    Universidad Rey Juan Carlos, Madrid, Spain.
    Rázuri, Javier G.
    Universidad Rey Juan Carlos, Madrid, Spain.
    Rios Insua, David
    Royal Academy of Sciences, Madrid, Spain.
    An Adversarial Risk Analysis Model for a Decision Agent facing Multiple Users2012In: 2012 3rd International Workshop on Cognitive Information Processing (CIP), IEEE Computer Society, 2012, p. 1-6Conference paper (Refereed)
    Abstract [en]

    We provide a model supporting the decision making process of an autonomous synthetic agent which interacts with several users. The approach is decision analytic and incorporates models forecasting the users' behavior. We sketch the implementation of our model with an edutainment robot.

  • 43.
    Everitt, Tom
    Stockholm University, Faculty of Science, Department of Mathematics.
    Universal Induction and Optimisation: No Free Lunch2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 44.
    Everitt, Tom
    et al.
    Stockholm University, Faculty of Science, Department of Mathematics.
    Lattimore, Tor
    Hutter, Marcus
    Free Lunch for Optimisation under the Universal Distribution2014In: 2014 IEEE Congress on Evolutionary Computation (CEC), New York: IEEE Computer Society, 2014, p. 167-174Conference paper (Refereed)
    Abstract [en]

    Function optimisation is a major challenge in computer science. The No Free Lunch theorems state that if all functions with the same histogram are assumed to be equally probable then no algorithm outperforms any other in expectation. We argue against the uniform assumption and suggest a universal prior exists for which there is a free lunch, but where no particular class of functions is favoured over another. We also prove upper and lower boundson the size of the free lunch.

  • 45.
    Fernaeus, Ylva
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Tholander, Jakob
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Patcher: A Tangible Game for Making Ecology Simulations in Museum Setting2007In: Tangible Play: Research and Design for Tangible and Tabletop Games, 2007, p. 25-28Conference paper (Other academic)
    Abstract [en]

    We present a tangible game for collaborative construction of ecological simulations. The system has been designed for and evaluated in the context of school classes visiting the Nature in Sweden exhibition at the Museum of Natural History in Stockholm. Based on card-based interaction using RFID-technology, the system affords discussion and collaborative play, leading to animated simulations displayed on a large screen. We discuss how technologies like this afford playful learning experience, especially in collaborative activities such as field trips to a museum.

  • 46. Fiebig, Florian
    et al.
    Lansner, Anders
    Stockholm University, Faculty of Science, Numerical Analysis and Computer Science (NADA). Royal Institute of Technology, Sweden.
    Memory consolidation from seconds to weeks: a three-stage neural network model with autonomous reinstatement dynamics2014In: Frontiers in Computational Neuroscience, ISSN 1662-5188, E-ISSN 1662-5188, Vol. 8, p. 64-Article in journal (Refereed)
    Abstract [en]

    Declarative long-term memories are not created in an instant. Gradual stabilization and temporally shifting dependence of acquired declarative memories in different brain regions called systems consolidation- can be tracked in time by lesion experiments. The observation of temporally graded retrograde amnesia(RA) following hippocampal lesions points to a gradual transfer of memory from hippocampus to neocortical long-term memory. Spontaneous reactivations of hippocampal memories, asobserved in place cell reactivations during slow wave- sleep, are supposed to driven eocortical reinstatements and facilitate this process. We proposea functional neural network implementation of these ideas and further more suggest anextended three-state framework that includes the prefrontal cortex( PFC). It bridges the temporal chasm between working memory percepts on the scale of seconds and consolidated long-term memory on the scale of weeks or months. Wes how that our three-stage model can autonomously produce the necessary stochastic reactivation dynamics for successful episodic memory consolidation. There sulting learning system is shown to exhibit classical memory effects seen in experimental studies, such as retrograde and anterograde amnesia(AA) after simulated hippocampal lesioning; further more the model reproduces peculiar biological findings on memory modulation, such as retrograde facilitation of memory after suppressed acquisition of new longterm memories- similar to the effects of benzodiazepines on memory.

  • 47. Fried, Dror
    et al.
    Shimony, Solomon Eyal
    Benbassat, Amit
    Wenner, Cenny
    Stockholm University, Faculty of Science, Numerical Analysis and Computer Science (NADA). KTH Royal Inst Technol, SE-10044 Stockholm, Sweden.
    Complexity of Canadian traveler problem variants2013In: Theoretical Computer Science, ISSN 0304-3975, E-ISSN 1879-2294, Vol. 487, p. 1-16Article in journal (Refereed)
    Abstract [en]

    The Canadian traveler problem (CTP) is the problem of traversing a given graph, where some of the edges may be blocked a state which is revealed only upon reaching an incident vertex. Originally stated by Papadimitriou and Yannakakis (1991) [1], the adversarial version of the CTP was shown to be PSPACE-complete, with the stochastic version shown to be in PSPACE and #P-hard. We show that the stochastic CTP is also PSPACE-complete: initially proving PSPACE-hardness for the dependent version of the stochastic CTP, and proceeding with gadgets that allow us to extend the proof to the independent case. Since for disjoint-path graphs, the CTP can be solved in polynomial time, we examine the complexity of the more general remote-sensing CTP, and show that it is NP-hard even for disjoint-path graphs.

  • 48.
    G. Allaart, Corinne
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences. Karolinska Institute, Sweden.
    Mondrejevski, Lena
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences. Karolinska Institute, Sweden.
    Papapetrou, Panagiotis
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    FISUL: A Framework for Detecting Adverse Drug Events from Heterogeneous Medical Sources Using Feature Importance2019In: Artificial Intelligence Applications and Innovations: Proceedings / [ed] John MacIntyre, Ilias Maglogiannis, Lazaros Iliadis, Elias Pimenidis, Springer, 2019, p. 139-151Conference paper (Refereed)
    Abstract [en]

    Adverse drug events (ADEs) are considered to be highly important and critical conditions, while accounting for around 3.7% of hospital admissions all over the world. Several studies have applied predictive models for ADE detection; nonetheless, only a restricted number and type of features has been used. In the paper, we propose a framework for identifying ADEs in medical records, by first applying the Boruta feature importance criterion, and then using the top-ranked features for building a predictive model as well as for clustering. We provide an experimental evaluation on the MIMIC-III database by considering 7 types of ADEs illustrating the benefit of the Boruta criterion for the task of ADE detection.

  • 49. Garg, Shilpa
    et al.
    Martin, Marcel
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Marschall, Tobias
    Read-based phasing of related individuals2016In: Bioinformatics, ISSN 1367-4803, E-ISSN 1367-4811, Vol. 32, no 12, p. 234-242Article in journal (Refereed)
    Abstract [en]

    Motivation: Read-based phasing deduces the haplotypes of an individual from sequencing reads that cover multiple variants, while genetic phasing takes only genotypes as input and applies the rules of Mendelian inheritance to infer haplotypes within a pedigree of individuals. Combining both into an approach that uses these two independent sources of information-reads and pedigree-has the potential to deliver results better than each individually. Results: We provide a theoretical framework combining read-based phasing with genetic haplotyping, and describe a fixed-parameter algorithm and its implementation for finding an optimal solution. We show that leveraging reads of related individuals jointly in this way yields more phased variants and at a higher accuracy than when phased separately, both in simulated and real data. Coverages as low as 2 x for each member of a trio yield haplotypes that are as accurate as when analyzed separately at 15 x coverage per individual.

  • 50.
    Giannoulis, Constantinos
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Zdravkovic, Jelena
    Stockholm University, Faculty of Social Sciences, Department of Computer and Systems Sciences.
    Model-Centric Strategy2IS Linkage: an Empirical Study2014Conference paper (Refereed)
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